"December 2005"

Agreement number: 05-CS-11015600-033

Includes bibliographical references (p. 11-12)

The distribution and status of bats in Montana remain poorly documented on US Forest Service Northern Region lands. This is of conservation interest because management activities on Forest Service lands (e.g., timber harvest, mine closures, closures of historic buildings) may have unintended consequences on habitats bats use for roosting and foraging and may therefore negatively impact bat populations. Additionally, the Northern Region has designated Townsend's Big-eared Bat (Corynorhinus townsendii) a Species of Concern requiring special attention; it is widespread but infrequently captured in Montana, with few documented hibernacula and maternity roosts and a reputation for being highly susceptible to human disturbance at roost sites. The Northern Region recognized the need for additional documentation of bats on Forest Service lands to address inventory and monitoring requirements, and initiated bat surveys in 2005 across the Region on selected National Forest (NF) Ranger Districts (RD). In Montana, these included Swan Lake RD-Flathead NF, Bozeman RD-Gallatin NF, Townsend RD-Helena NF, Libby RD-Kootenai NF, and Judith RD-Lewis & Clark NF. Following a modified protocol based on the Oregon Bat Grid system, crews surveyed non-randomly chosen suitable habitats within randomly chosen 10 x 10 km2 sample units in each RD; ten sites (often two/sample unit) on each District were sampled, for a total of 50 sites surveyed on Northern Region lands in Montana. Thus, this approach is primarily targeted at identifying species richness within grid cells; inferences on rates of occupancy are limited to the percent of 10 x 10 km2 grid cells where a species was detected within each sampled RD. Eleven species of bats, represented by 795 total individuals, were captured during late-June to mid-August 2005. Species captured included Townsend's Big-eared Bat at two sites, Big Brown Bat (Eptesicus fuscus) at 14 sites, Hoary Bat (Lasiurus cinereus) at 20 sites, Silver-haired Bat (Lasionycteris noctivagans) at 25 sites, California Myotis (Myotis californicus) at nine sites, Western Small-footed Myotis (M. ciliolabrum) at eight sites, Western Long-eared Myotis (M. evotis) at 26 sites, Little Brown Myotis (M. lucifugus) at 32 sites, Fringed Myotis (M. thysanodes) at four sites, Long-legged Myotis (M. volans) at 23 sites, and Yuma Myotis (M. yumanensis) at two sites. No bats were captured at five of the sites sampled, although presence of bats was noted at each. The 2005 field survey filled important gaps in documented distributions in Montana, adding several new county records and underscoring the need for additional survey effort to define bat distributions on USFS landscapes more fully. A summary of all existing bat records across the region clearly shows large distribution gaps for all species, further underscoring the need for addition surveys. In particular, large portions of the Beaverhead-Deerlodge NF, Custer NF, Flathead NF, Gallatin NF, and Lewis and Clark NF lack records for any bat species. We recommend that the USFS Northern Region continue with a grid-based random sampling scheme stratified by ecoregion or Ranger District, resulting in a site-occupancy approach that allows for valid inference of presence across the selected stratum. A grid-based sampling scheme is an important monitoring approach that should be extended beyond USFS lands and coordinated with other partner agencies and organizations to guide effective bat management across the state

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